1. Field of the Invention
The present invention relates generally to a communication system and a communication method thereof, and more particularly, to a communication system including a femto base station having a plurality of antennas and a communication terminal, and a communication method thereof.
2. Description of the Related Art
Generally, communication system includes of a plurality of macro cells. The macro cells are each administrated by a macro base station that provides a communication service to communication terminals within the corresponding macro cell.
Currently, a signal environment for each communication terminal is changeable in a specific macro cell, but a macro base station cannot afford to consider signal environment for each communication terminal when providing communication service. Consequently, the quality of the communication service may deteriorate and delays may occur with the communication service.
To remedy this problem, a mediation device, such as a repeater or a remote unit, can be installed between a macro base station and a communication terminal in a communication system. However, the macro base station and the mediation device are installed by a service provider, which increases communication system costs of the service provider. Additionally, it is often difficult to connect a macro base station to a mediation device in communication system.
Therefore, a proposed solution to overcome the above-described problems, is installing a femto base station within a macro cell, independent from the macro base station in communication system. A femto base station is a home base station that is installed, e.g., at home or office, depending on user need.
For example, a femto cell can be ubicell for a Wideband Code Division Multiple Access (WCDMA) High Speed Packet Access (HSPA) standard. This type of femto cell improves a signal environment of communication terminals within a cell area of the femto base station and improves the quality of a communication service without any additional cost for service providers.
However, by adding an independent femto base station, the signals of macro base station and femto base station may interfere with each other. Further, signals of femto base stations may also interfere with signals of a communication terminal.
For example, a femto base station sends and receives a signal through an antenna having an omni-directional radiation pattern, so that a communication terminal located within a femto cell of the femto base station may simultaneously receive a signal of the femto base station and macro base station, which can generate interference. Further, signals of the communication terminal may also experience interference from received signals of other femto base stations.